Thrust washer

Abstract

Oil grooves (40) formed in at least one of surfaces of a ring-shaped member (30) each have a longitudinal direction that forms an angle falling within a range of from 40 degrees to 75 degrees with respect to a radial direction of the ring-shaped member, and are arranged at equal intervals in a circumferential direction of the ring-shaped member (30). The oil grooves (40) include communicating oil grooves (40A) and non-communicating oil grooves (40B) formed to extend to the vicinity of an outer peripheral end (34), and are arranged with periodic regularity in the circumferential direction of the ring-shaped member (30). In addition, a communicating oil groove area ratio expressed by Expression: “S1/(S1+S2)” falls within a range of from 0.15 to 0.85, where S1 represents a sum of plane areas of the communicating oil grooves (40A), S2 represents a sum of the non-communicating oil grooves (40B).

The invention claimed is: 
     
       1. A thrust washer, comprising a ring-shaped member made of a material containing a resin, the ring-shaped member having a front surface and a back surface,
 wherein at least one of the front surface or the back surface of the ring-shaped member slides against another member, 
 wherein at least one of the front surface or the back surface has four or more oil grooves, each being a flow path for lubricating oil, 
 wherein an oil groove carrying surface is a surface to slide against the another member, 
 wherein the oil grooves each have a longitudinal direction that forms an angle falling within a range of from 40 degrees to 75 degrees with respect to a radial direction of the ring-shaped member, and are arranged at equal intervals in a circumferential direction of the ring-shaped member, 
 wherein the oil grooves are formed of (i) communicating oil grooves, each having opening portions at an inner peripheral end and an outer peripheral end of the ring-shaped member, respectively, and each being a recessed portion formed continuously to connect the opening portion at the inner peripheral end and the opening portion at the outer peripheral end, and (ii) non-communicating oil grooves, each having an opening portion only at the inner peripheral end of the ring-shaped member, and each being a recessed portion formed continuously to extend from the opening portion at the inner peripheral end to a vicinity of the outer peripheral end, 
 wherein a total number of the communicating oil grooves is two or more, 
 wherein the communicating oil grooves and the non-communicating oil grooves are arranged with periodic regularity in the circumferential direction of the ring-shaped member, and 
 wherein a communicating oil groove area ratio expressed by Expression (1):
   Communicating oil groove area ratio= S 1/( S 1+ S 2) 
 
 
       falls within a range of from 0.15 to 0.85, where S1 represents a sum of plane areas (mm 2 ) of first to n-th communicating oil grooves, S2 represents a sum of plane areas (mm 2 ) of first to m-th non-communicating oil grooves, “n” represents a total number of the communicating oil grooves, and “m” represents a total number of the non-communicating oil grooves. 
     
     
       2. The thrust washer according to  claim 1 , wherein a total number of the oil grooves falls within a range of from 6 to 18. 
     
     
       3. The thrust washer according to  claim 1 , wherein the communicating oil groove area ratio falls within a range of from 0.230 to 0.680. 
     
     
       4. The thrust washer according to  claim 1 , wherein the communicating oil groove area ratio falls within a range of from 0.310 to 0.520. 
     
     
       5. The thrust washer according to  claim 1 , wherein the angle formed between the longitudinal direction of each of the oil grooves and the radial direction of the ring-shaped member falls within a range of from 40 degrees to 65 degrees. 
     
     
       6. The thrust washer according to  claim 1 , wherein an oil groove length ratio expressed by Expression (2):
   Oil groove length ratio= L 1/( L 1+ L 2) 
 
       falls within a range of from 0.90 to 0.99, where L1 represents a length (mm) in a longitudinal direction of a non-communicating oil groove of the non-communicating oil grooves, and L2 represents a length from an outer periphery-side most distal end portion of the non-communicating oil groove to the outer peripheral end of the ring-shaped member in a direction parallel to the longitudinal direction of the non-communicating oil groove. 
     
     
       7. The thrust washer according to  claim 6 , wherein the oil groove length ratio falls within a range of from 0.95 to 0.99. 
     
     
       8. The thrust washer according to  claim 1 , wherein the resin comprises a polyphenylene sulfide resin.